Automatic temperature control system



11, 19441. T. J. LEHANE Em. 2,346,592

AUTOMATIC TEMPERATURE CONTROL SYSTEM Filed May 2, 1942 3 Sheets-Sheet l April 11, 1944 y T. J; LEHANE ET AL 2,346,592

AUTOMATIC TEMPERATURE CONTROL SYSTEM Filed May 2, 1942 3 Sheets-Sheet 2 OUTSIDE 1 59 April '11, 1944.

T. J. LEHANg-z ET AL AUTOMATIC TEMPERATURE CONTROL SYSTEM Filed May 2, 1942 3 Sheets-Sheet 3 Patented Apr. Il, 1944 2,346,592 AUTOMATIC TEMPERATURE CONTROL SYS Timothy J cago, Ill.,

TEM

Lehane and Everett H. Burgess, Chiassgnors to Vapor Car Heating Company, Inc., Chicago, Ill., a corporation of New York Application May 2, 1942, Serial No. 441,426

17 Claims.

This invention relates to certain new and useful improvements in a temperature controlling and Ventilating system for an enclosed space, more particularly a railway car. Steam will generally be used as a heating medium while the Ventilating and cooling mechanisms will be electrically driven. The controlling apparatus is electrically actuated under either manual control or thermostatic control, or both.

The thermostats used are preferably of the mercury-column type, each designed to function (that is complete an electric circuit therethrough) at a certain deiinite temperature, but in most instances the thermostat is provided with an electric heater in the form of a coil associated therewith for adding a measured amount of auxiliary heat so that the thermostat will actually function at a temperature somewhat lower than that actually prevailing in the surrounding atmosphere. The majority of the thermostats function at predetermined temperatures within the car, or other enclosed space, although there are certain thermostats which respond to atmospheric changes outside of the space.

Much of the control mechanism is positioned in or associated with a suitable control panel mounted in an accessible position within the space or car, said panel being indicated by a simplified wiring diagram in the present disclosure.

The principal object of this invention is to provide an improved temperature control and ventilating system of the general type briey described hereinabove and disclosed more in detail in the specifications which follow.

Another object is to provide means, under manual control, for circulating air through the car, together with means for heating this air or cooling the air as prevailing temperature conch'- tions within the space or car may require.

Another object is t provide thermostatic means responsive to outside temperature changes for adjusting the inside thermostatic means to permit the inside temperature to increase when the outside temperature falls below a predetermined minimum or rises above a predetermined maximum.

Another object is to provide means for cooling the interior space at any time that inside temperature conditions may require but preventing the use of the heating means whenever the cooling is affected.

Another object is to provide manually adjustable electrically actuated means for raising or lowering the range of temperatures at which the inside thermostats function without affecting the spacing between the individual operating temperatures.

Other objects and advantages of the invention will be more apparent from the following detailed description of certain approved forms of apparatus and electrical connections operating in accordance with the principles of this invention.

In the accompanying drawings:

Fig. l is a diagrammatic outline, on a small scale, ol a railway car provided with this improved system.

Fig. 2 is a transverse vertical section, on a larger scale, taken substantially on the line 2-2 of Fig. 1.

Fig. 3 is for the most part a wiring diagram of an approved form of the control system.

Fig. 4 is a more detailed wiring diagram of the control mechanism for the "floor heat, as also shown in the upper portion of Fig. 3.

Fig. 5 is a diagram of the controlling valve for the overhead heat.

Fig. 6 is a detail view corresponding to the upper left hand corner of Fig. 3. but showing a modification.

Fig. 7 is a similar view of a modied thermostatic selector for the cooling system.

Fig. 8 is a wiring diagram, similar to Fig. 3, showing certain modifications in the controlling circuits.

Referring rst to Figs. 1 and 2, the railway car shown in outline at I is provided with normally closed doors 2 at its ends communicating through passage-ways 3 extending around the interior compartments 4 to the main interior space 5 of the car.

Ventilating air is circulated through upper conduits 6 (Fig. 2) within the car and projected through outlets in said conduits into the car and suitable heating means for this overhead air is provided (not here shown in detail), said heating means being under the control of a thermostat 'l positioned in the main body of the car at about the ve foot level. The air in conduits 6 is also cooled when necessary by suitable refrigerating means under the control of thermostats 8 and 9 which may be situated within the car adjacent the thermostat l. Radiators l0 are also provided in the lower side portions of the main space within the car for directly heating the air therein, the valves l l for admitting steam to these radiators being under the control of a thermostat I2 suitably located adjacent the oor of the car. In the present arrangement the car will normally be heated by imparting heat to the circulating or "overhead" air discharged from the conduits B, the "floor heat from the radiators lil being in the nature o.f an auxiliary heating means for providing heat when the alrcirculating blower is not in operation or under extreme temperature conditions when the heating capacity of the overhead heat is inadequate. A heating system of this general type is disclosed more in detail and claimed in the copending application of the present inventors, Serial No. 427,257, filed January 19, 1942.

Referring now more particularly to Fig. 3, an approved form of controlling system will be described. The positive and negative mains I3 and I4 shown respectively at the right and left of this view are connected with the corresponding sides of a suitable source of electric energy. At the lower end of this drawing. at I5, is indicated the motor (provided with field I6) which drives the blower or fan for forcing ventilation air through the conduits 6. A blower fan switch, indicated generally at A, comprises a plurality of simultaneously operated members I1, I8, I9 and 20. This switch is manually controlled and it will be understood that when the switch members I1, I8 and I9 are open the member 2D will be closed and vice versa. When switch member I1 is closed .the blower motor I5 will be energized in an obvious manner by current flowing from main I3 to main I4 at the lower end of Fig. 3.

As will be hereinafter apparent, neither the overhead heat nor the cooling system will be operative unless the blower is in operation to circulate the air, and consequently it is desirable that the oor heat system shall be operative at such times as the blower is not operating in order that some heat will be available at this time. Consequently the switch is closed whenever the main switch is open. thus establishing a circuit from positive main I3. through wire 2|, switch 20, terminal 22, wire 23, resistor 24, floor heat relay 25, resistor 26, and wire 21 to the negative main I4. The oor heat relay 25 and associated parts are shown at the upper central portion of Fig. 3, but are also shown more in detail in Fig. 4, which will rst be described. As shown in Fig. 4, the relay coil 25 is de-energized so that the core 28 within said coil will be lifted by spring 29 and, through stem 30, will lift the contact plate 3I into engagement with the xed contacts 32 and 33 and at the same time lift and disengage contact plate 34 from the xed contacts 35 and 36. The Valve II (see also Fig. l) is of the normally open type and comprises an inlet pipe 31 leading n to the valve chamber 38 and a supply pipe 39 leading from this chamber into the radiator. such as II). The spring 46 will normally pull out the valve stem 4I and withdraw valve 42 from the entranse of pipe 39, thus permitting steam to flow to the radiators.

The floor heat thermostat I2 is of the doublebulb type comprising an upper bulb 43 exposed to the atmosphere and a lower bulb 44 provided with a surrounding electric heating coil 45. The mercury column 46 is always in engagement with a lower xed contact 41, while at a certain functioning temperature (for example 78) this mercury column will engage the upper fixed contact 48. It is to be assumed that the prevailing atmospheric temperature adjacent the oor of the car plus the heat added by coil 45 will cause the mercury column to engage the upper contact 4B, at winch time a current will ow through the thermostat I2 between the terminals 49 and 50 of the relay coil 25, thus de-energizing this coil, as shown in Fig. 4. In other words the floor heat temperature requirements are now satisfied at the location of thermostat I2. A circuit will now be completed from the positive main I3 through wire 5 I, contacts 32, 3l and 33, wire 52, solenoid coil 53, and wire 54 to the negative main I4. The energization of coil 53 will draw in the core 55 at the end of valve stem 4I, thus causing the valve 42 to close against the opposition of spring and cutting off the further flow of steam to the radiators. When the temperature at thermostat I2 falls so as to break the circuit through the thermostat at 48, the relay 25 will again be energized so as to pull down the contact 3l and break the circuit through the valve coil 53, again opening the valve 42 and admitting steam to the radiators.

The heating coil on the floor heat thermostat I2 is normally energized by current flowing from positive main I3 through the selected resistor of potentiometer P (hereinafter described) wire 56, coil 45, wire 51 to terminal 58, balancing resistor 53, and outside thermostat to the negative main I4. It will be assumed that this continuously flowing current will normally cause the thermostat I2 to function at the selected temperature, for example 78. However, when the temperature has fallen somewhat and the valve has been opened as described, the contact plate 34 will be drawn down into engagement with xed contacts 35 and 36, thus causing a current to now from wire 5I through these contact plates, wire 6 I, cycling resistor 62, wire 63 to terminal 64, wire 56 and thence through the heating coil y45. This additional current will further increase the hout imparted to the thermostat by coil 45 so that the operation of the thermostat will be expedited, that is it will function at a somewhat lower temperature. This so-called cycling action will expedite the operation of valve II so that the supply of steam to the floor heat radiators will be cut on and olf at more frequent intervals.

While the general operation of the thermostat and relay system for controlling the iloor heat is more completely shown in Fig. 4, a more simpliled disclosure of the same system is shown in the upper central portion of Fig. 3 and this same simplified showing is used for most of the other thermostatic assemblies hereinafter referred to, the detailed operation of which should be apparent from the similarity to Fig. 4.

The upper deck of a manually-operated potentiometer P for adjusting the functioning temperature of the floor heat thermostat I2 is shown in the upper right corner of Fig. 3, whereas the exactly similar lower deck of this potentiometer is indicated at P near the lower right hand side of this gure. The centrally pivoted contact member 65 is always in engagement at its right hand end with the arcuate contact or series of contacts 66 which is connected with the positive main I3. Contact B5 is adjusted about its central axis by the knob or handle 61, and the left hand end of this contact is selectively engaged with any one of the arcuate series of five spaced contacts 68, which contacts form one terminal ci the altemative resistors 63 to 13 inclusive which are connected in parallel at their other ends by a wire 14 which connects with one end of the wire leading to the heating coil 45 on thermostat I2. It will be seen that as potentiometer F is adjusted by rotating the knob 61 one or another of the resistors 69 to 13 inclusive will bc connected in series with the heater 45 thus` selecting the current that will flow through coil 45 and determining the temperature at which thermostat I2 will function. What may be assumeti to be the normal position of the potentiometer is indicated in solid lines in Fig. 3. the resistor 1I now being in series with the heater G and with the parts so positioned we may assume that the thermostat I2 will function at 78. The resistors 69 to 13 are of different values so that as the controller 61 is rotated in either a clockwise or counter-clockwise direction, the amount of heat added to the therrmostat I2 will be raised or lowered so as to selectively adjust 'the functioning temperature of this thermostat.

It will be noted that resistors and 45" (havlng the same resistance as the heater 45) are arranged in similar circuits parallel thereto so that the current flowing through each of these 'parallel circuits will be the same at all times. It will be understood that in the simple example here shown only one floor heat thermostat I2 is illustrated, but the floor heat radiators might be divided into as many as three groups, in which case the heaters for the other two thermostats would be indicated by the resistors 45 and 45". Of course, each of these heaters would be associated with a thermostat and cooperating relay Vsimilar to the ones shown in Figs. 3 and 4 and 'energized through parallel circuits. The lower deck P of the potentiometer P may be exactly the same as the upper deck, both decks being actuated by the same manually operated controller 61. The individual parts of the lower deck P' are indicated by the same reference characters primed as are shown on potentiometer P. The right hand row of contacts on deck P' are energized from main I3 through the wire 15. The lower deck P' adjusts the heaters for the "overhead thermostat" 1 and the two cooling thermostats 8 and 9, already referred to. The

arrangement of the manual potentiometer in A two simultaneously operated decks P and P', each adjusting the heaters for three controlling thermostats is for the purpose of properly balancing the wiring system.

As will be more apparent hereinafter, each of the several thermostats hereinabove mentioned is adapted to function at a certain definite temperature inside the space or car, or a certain temperature to which this thermostat is adjusted by the potentiometer P. It will be noted that the adjustments accomplished by this potentiometer moves the entire scale of these functioning temperatures either up or down so that the relative arrangement of these temperatures and the spacing therebetween is not affected by the movement or adjustment of the potentiometer. The additional adjustments of the inside thermostat by the cycling resistors or by the outside thermostat as described elsewhere herein, are not dependent upon the potentiometer P which merely serves to adjust the entire range of operating temperatures either up or down as may prove to be desirable.

The overhead heat relay 'I6 (see upper center of Fig. 3) will normally be energized (when fan switch A is closed) by the following circuit: from positive main I3 through wire 11, switch I9, wire 18, wire 19, resistor 80, wire 8|, relay coil 16. wire 82, resistor 83 and wire 84 to the negative main I4. When the relay 16 is thus energized it will draw the movable contact into engagement with the fixed contacts 86 and 81, thus completing a valve-energizing circuit as follows: from main I3 through wire 86, relay contacts 86, 85 and 81, wire 89, solenoid coil 90, and wire 9| to the negative main I4. The overhead heat valve differs from the valve shown in Fig. 4 in that it is normally closed by spring 92 (Fig. 5) but when solenoid 90 is energized (through the circuit last described) it will draw in the core 93 and open the valve in opposition to the spring 92. When the predetermined functioning temperature (for example 76) is reached at the overhead thermostat 1 a short circuit will be formed through this thermostat between the relay terminals 94 and 95 at the ends of relay coil 16, thus de-energizing this relay and permitting the contact to open, thus breaking the circuit through solenoid coil and permitting the overhead steam valve to close. In other words the overhead heat will remain in operation as long as the effective inside temperature at thermostat 'I is below 76 but will cease operation when the inside temperature rises above 76.

The overhead heat thermostat 1 is provided with an adjusting heating coil 98 energized through the following circuit: from positive main I3 through wire 15, potentiometer P', wire 95'.. wire 91. heater 9B, wires 99 and |00 to the terminal 58 and thence as before to the negative main I4. When the inside temperature is below the normal functioning temperature of thermostat 1 (for example 76) and the relay 16 is energized so as to draw down the bridge contact 85. so that the overhead valve will be open to admit steam to the system, another circuit will be completed from main I3, wire 88, and relay contacts 66, 85 and 81, through wire IUI, cycling resistor |02, wire |03, to terminal |04 and thence as before through wire 91 and the thermostat heater 98. This temporarily operating auxiliary parallel circuit will permit additional current to iiow through the heater 98 and as a result, somewhat lower the functioning temperature of the thermostate 1. but as soon as the valve is closed and the relay contacts are again separated, the original current will again be restored in heater 98 and the thermostat will again function at 76,

When the overhead valve is closed and the relay 16 is de-energized, another relay contact |05 will be moved into engagement with the pair of fixed contacts |06 and |01, thus completing another partial circuit as follows: from main I3, through wire 88 and relay contacts |06, |05 and |01, through wire |08, cycling resistor |09, and wires |I0. 63 and 56 to the heater 45 on thermostat I2. This will provide an additional path of current to the heater 45 so that this floor heat thermostat I2 will function at a somewhat lower temperature providing the necessary floor heat circuits are otherwise completed. This cycling connection expedites the operation of the Iioor heat at such times as the overhead heat is off and vice versa. In other words, as long as the temperature is above '16 and the overhead heat is off, current will ow through resistor |09 to the heater 45 on the floor-heat thermostat I2 and that thermostat will function at a lower effective temperature fsuch as 73) so as to keep the floor heat off until the car temperature falls below 73. Before this can occur the temperature will drop below 76 and the overhead heat will be turned on." At this time the circuit through resistor |09 will be broken and the current reduced through heater 45 so that the effective temperature at heater 45 will be lowered and the functioning temperature of thermostat I2 will be raised toward the normal temperature of 78 for which it is designed. In short, the greater the proportion of the time that the overhead heat is in operation, the higher the minimum temperature at which the floor-heat will function, although the overhead heat will always be called upon first to satisfy the heat requirements if these are within its capacity.

Assuming that the relay 16 is deenergized for any reason, as when the actual inside car temperature is about 76, the resistor |08 will be effective to cause the floor-heat thermostat |2 to function at 73, that is floor heat will be active below 73 but will be turned off when the car temperature rises above 73.

At (lower central portion of Fig. 3) is shown an interlock thermostat which is positioned outside the car so as to function at a predetermined exterior temperature (for example 40) to complete a circuit therethrough to short circuit an interlock relay through the wires I I2 and ||3 connecting the mercury column with the terminals ||4 and ||5 at the ends of relay coll I I6. Therefore at all outside temperatures above 40 a circuit will be completed from positive main I3, through wire resistor H8, wire ||9, thermostat wire |20, resistor |2| and wire |22 to the negative main |4. At such times the relay coil IIB will not be energized and the bridging contact |23 will be in engagement with the fixed contacts |24 and |25. At this time the contact |26 will be lifted out of engagement with the iixed contacts |21 and |28. On the other hand, when the temperature at thermostat falls below 40 the circuit through this thermostat will be broken and the relay ||6 will be normally energized to draw down contact |26 into engagement with the fixed contacts |2'I and |28 and to move the bridging contact |23 out of engagement with contacts |24 and |25.

It will be rst assumed that the cooling thermostat 8 normally functions at 78, that is if the inside temperature rises above 78, this thermostat will endeavor to place the cooling system in operation. A heating circuit for this thermostat will flow from main I3, through wire |5 and potentiometer P' to and through wire l 29 and heating coll |30 on thermostat 3 and thence through wire as before, to the terminal 58. It will be assumed that when this current is flowing the thermostat 8 will function at 78 to complete the following circuit therethrough: from arm |9 of switch A, through wire 18, wire 3|, relay contacts |24, |23 and |25, Wire |32, resistor |33, thermostat 8, wire |34, relay |35, and wire |36 to the negative main I4. The energization of relay |35 will draw down the contact |31, thereby completing a circuit through wire |38 extending from wire 'I9 to the negative main. This will close a circuit through the refrigerator motor |39 so as to actuate the refrigerating system, and will also energize the solenoid |40 which opens the valve admitting refrigerant to one section of the evaporator or cooling coil. In other words, as long as the space temperature is about 78 the refrigerator motor will be in operation and refrigerant will be admitted to a portion of the evaporator. This operation will continue until the temperature again falls below 78, whereupon the cooling system will be stopped.

The cooling system herein disclosed is of the type more fully disclosed and claimed in the copending application of the same inventors, Serial No. 427,258, filed January 19, 1942. This system comprises a split evaporator, the first section of which is normally used whenever cooling is required (as disclosed hereinabove), the second section being only used when the rst section is insufficient to satisfy the temperature requirements. This second section is controlled by the thermostat 9 which does not function until an effective space temperature of is reached. Thermostat 9 is provided with an auxiliary heating coll |42 energized through a circuit extending from wire 96, through wire |4|, heater |42 and Wire |43 to the wire |00. The temperature prevailing in the space plus the heat added by coil |42 will cause thermostat 9 (at 80 for example) to close a circuit extending from wire 'i9 through resistor |44, wire |45, thermostat 9, relay coil |46, and wire |4'I to the negative main |4. The energizatlon of coil |46 will move the contact |48 into engagement with the fixed contacts |49 and |50 and will also move the second contact |5| into engagement with the fixed contacts |52 and |53. The closing of this second set of contacts will complete a circuit from wire I9 through wire |54, the relay contacts and solenoid coil |55, through wire |56 to the negative main I4. The coil |55 will open the valve to the second section of the evaporator. It will be understood that the compressor |39 is still in operation since the first section of the evaporator is still operating. At the same time the relay |46 will cause a second circuit to be completed from wire 96 through wire |51, cycling resistor |58, wire |59, contacts |49, |48 and |50, and wire |60 to the wire I 00. This will provide a second path for the current from wire 96 to wire |00, in parallel with the circuit through heater |42, so that the current iiow through heater |42 will be reduced and consequentlyl the functioning temperature of thermostat 9 will be temporarily lowered. This will expedite the closing of the valve controlled by coil |55 so that this auxiliary section of the evaporator will have a cycling operation.

It will be noted that the heating currents for both cooling thermostats 8 and 9, as well as for the overhead heat thermostat all flow through the lower deck P of the manually operated potentiometer and are simultaneously and proportionately adjusted thereby at the same time that the floor heat thermostats are controlled by the other deck P of this potentiometer. It will now be noted that all of these thermostats controlling heating circuits flow eventually through the same terminal 58 (upper left of Fig. 3) and thence through the resistances 59 and |6| in series to the negative main |4, as long as the temperature outside of the space is below 0. As has already been described, the thermostat 60 is adapted to function at (for example) 0 to close a bridging circuit through wires |62 and |63 around the resistance ISI. Therefore the resistance |6| will not normally be in the heating circuit but below 0 this resistance |6| will be added to all of the heating circuits so as to decrease the heating current applied to all of the thermostats and therefore raise the effective temperatures at which heat will be cut off at each of these thermostats.

A modification of this portion of the system is shown in Fig. 6 which is to be substituted for the partial circuits shown in the upper left hand corner of Fig. 3. The structure is the same as previously described with the exception that for the resistor |6| a heating coil |6|' associated with the thermostat 60 is substituted. When the outside temperature at this thermostat 60 falls below 0 the thermostat will break the circuit through wires |62 and |63 and instead the circuit will now ilow through wire |64, heating coil |6| and wire |65. It will be understood that the coil |6|' will function the same as the resistor |6|, previously described, `to add resistance in the heating circuits while at the same time it will impart heat to the thermostat 60 so as to raise its functioning temperature. For example this coil may add 20 of heat to the thermostat 60 so that the thermostat will actually close its circuit at 20 instead of 0 for which it is designed. Therefore at the actual outside temperature of the thermostat 60 will act to place the resistor |6I' in the circuit, but this resistor acting as a heater will at once again close the circuit through the thermostat so as to short-circuit the coil |6|' and restore the original current through the heating circuits. This cycling operation will repeat itself at less frequent intervals as the actual outside temperature falls further below 0 until the actual temperature has fallen below -20, whereupon the circuit through the thermostat will remain broken in spite of the heater |6I' so that this heater will remain continuously in the circuits and the heating current for the other heat controllirg thermostats will remain continuously1 decreased as long as the outside temperature is below -20.

A cooling selector thermostat |66 (lower central portion of Fig. 3) is located outside of the enclosure so as to be responsive to the prevailing outside temperature and is in a circuit extending from the positive main I3 through wire |61, resistor |68, thermostat |66, and wire |69 to the wire |00. Accordingly, when a predetermined temperature (for example 85) is reached outside of the car, this circuit will be completed so as to place the resistor |68 in parallel with `the adjusting potentiometer P thus decreasing the effective currents in the heaters for the cooling thermostats, that is the cooling system will not become effective until slightly higher inside temperatures are reached. This is desirable since the inside temperature should be permitted to rise somewhat as the outside temperature increases, that is there should not be too much difference between the inside and outside temperatures. In the present example, the inside temperature is permitted to become somewhat higher when the outside temperature rises above 85.

A modiflcation of this portion of the system is indicated in Fig. 7. This showing is similar to the cooling selector circuit just described. A heating coil is applied to the thermostat |66 and is connected in parallel with this thermostat across the terminals |1| and |12.

At those outside temperatures below (for example) 100 there will normally be no circuit completed through the thermostat but a small amount of current will continuously flow through the resistances |10 and |68 in series. The resistance |10 is so designed that this heater will add approximately of heat to the thermostat so that it will start to function at an actual outside temperature of 85. At this effectlve temperature of 100 the thermostat will then function as if the outside temperature were 85 so that the circuit will be completed through the thermostat and the heating coil |10 will be temporarily de-energized. The current then flowing through the resistor |68 will be sufllcient to materially change the setting of the coollnglthermostats 0 and 9 so that a -40, whereupon the interlock thermostat greater degree of heat will be permitted within the car space. However, the effective temperature at thermostat |66 will immediately be lowered since the heating coil |10 is no longer energized and consequently the resistance |10 will be restored to the circuit thus again cutting down the current through this shunt circuit to a negligible minimum. In other words the thermostat |66 will again function at an actual outside temperature of 100 instead bf 85. This cycling operation will repeat itself as long as the actual outside temperature remains below 100, but above 100 the thermostat |66 will remain continuously closed. In short, between 85 and 100 outside temperature the permissible inside temperature will be progressively raised, the cooling system being least effective at 100.

Referring now again to the general operation of the system as disclosed in Fig. 3, the control apparatus is in general responsive to changes in the prevailing temperature within the car. Assuming rst that the blower switch A is closed and that the inside temperature is above 76 but below 78, the air circulation system will con-' tinue to operate but only for Ventilating purposes since this air is neither being cooled or heated. Assuming that the inside temperature rises to 78, or above, the refrigeration motor |39 will be started and the rst unit of the cooling system will be put in service. 1f this first unit proves to be insufficient to lower the temperature below 78 and the temperature continues to rise to 80 or above, the second unit of the cooling system will be put in service under the intermittent cycling control of the resistor |58. Both units of the cooling system will operate until the inside temperature falls below 80, and the first unit will continue until the inside temperature has fallen below 78, whereupon the cooling system will cease to function. If, during this time, the outside temperature should rise to or above, the inside ternperature will be permitted to rise somewhat higher than 80 so as not to maintain too great a difference between the inside and outside temperatures.

On the other hand, assuming that the inside temperature should fall below 76 from the intermediate Ventilating range first described, the

- overhead heat will then be put in operation under the control of thermostat 1 and ordinarily this overhead heat only will be used to restore the necessary temperature within the car unless the outside temperature should fall below ||I would permit the floor heat thermostat 45 to put the floor heat radiation in service below an inside temperature of 73. It will be understood that if (regardless of the outside temperature) the switch A should be opened and the air circulation stopped, the floor heat will be effective at or below 73 inside temperature to heat the space within the car. If at any time the outside temperature should fall below 0, the current in the heat-control thermostat circuits will be temporarily adjusted so as to permit the heating systems to maintain a somewhat higher temperature within the car.

In the above description the inside control temperatures assumed by way of example have been referred to, but it is to be noted that this entire range of inside controlling temperatures can be raised or lowered within certain limits by the use of the manual potentiometers P and P.

In Fig. 8 is illustrated a modification of the controlling system in which the outside interlock thermostat I is omitted so that the outside temperature has no direct control over the change from the heating to the cooling side of the system. Both the heating and cooling are dependent upon the temperatures prevailing within the space, and the cooling system is operative at any time, regardless of the prevailing outside temperature, providing the inside temperature calls for cooling and the Ventilating blower is in operation. Most parts shown in Fig. 8, which are not specifically referred to hereinafter, are the same as has already been described in connection with Fig. 3. As already described, the interlock thermostat I I I is omitted but the controlled relay IIS' is the same as the relay ||6 shown in Fig. 3 and is normally energized through the same circuit as before. The first cooling thermostat 8 now completes a circuit extending directly from wire 19, through wire |13, resistor |33, thermostat 8, wire |34, solenoid coil |35, and wire |36 to the main I4 so that at 78 inside temperature the coil |35 will be energized to draw down the contact |31 and complete the circuits through the refrigerating motor |33 and the valve-opening solenoid |40 for the i'lrst unit of the evaporator. The cooling relay |35, in addition to the contact |31, already described, operates a second contact |14 so that when the cooling system is started another circuit will be completed to de-energize the normally energized relay ||6, as follows: from one terminal |15 of relay ||6, through wire |16 to fixed contact |11, movable contact |14, fixed contact |18, wire ISU to terminal |8I, and wire |82 to the other terminal |83 of relay IIS'. Since ||6' is now deenergized, the contact |26 will be drawn out of engagement with the fixed contacts |21 and |28 so that the circuit through wire 23 to the floor heat control system will be broken at contact |26 and the floor heat will not be operative while the blower fan switch A is closed (that is while contact 28 is open). At the same time a holding" circuit will be completed from terminal |15, through wire |84, relay contacts |25, |23 and |24, wire |85, additional contacts |86, |81, and |88 of the overhead heat relay 16, wire |89, terminal |8I, and wire |82 to the other terminal |83 of relay coil ||6'. The new movable contact |81 of the overhead heat relay 16 will now be closed since the temperature is above 76 (the cooling system is in operation). Therefore, this holding circuit will remain closed to de-enei'- gize the relay IIB' even though the contact |14 of relay |35 should open, due to the cooling system being satisfied by the temperature falling slightly below 78". Even though the inside ternperature is above 76, the overhead heating systern cannot operate since the wire 88 leading to the overhead heat valve 98 extends (in this modication) from the wire 23, which is now de-energized. From the time that the action of the first cooling relay has closed the contact |14 until the holding circuit is broken by the space temperature falling below '16 (thus again energizing the overhead heat relay 18, so as to open the relay contact |81) the interlock relay I|6' will remain de-energized so as to hold both heating mechanisms out of service. In short, the cooling system will be operative at any time, regardless of the outside temperature, providing the blower fan is in operation and the inside temperature is'above '78", and no part of the heating system can operate until the inside temperature again falls below 76. It will be understood that all of the temperatures just referred to assume a fixed setting of the potentiometers P and P'. The scale of these controlling temperatures can be raised or lowered by a suitable adjustment of these potentiometers.

We claim:

l. In combination with temperature regulating apparatus comprising means for supplying heat to or withdrawing heat from a space, and control mechanism comprising a plurality of thermostats each adapted to function at a predetermined space temperature to cause a portion of said apparatus to operate or cease to operate, an electric heater cooperating with each thermostat to selectively determine the functioning temperature of that thermostat, heater-energizing circuits connected in parallel with one another and a manually operable potentiometer adapted to connect the same selected resistance in series with each of these heaters whereby the entire scale of functioning temperatures is adjusted up or down without changing the spacing between the functioning temperatures of the several thermostats.

2. In combination with temperature regulating apparatus comprising means for supplying heat to or withdrawing heat from a space, and control mechanism comprising a plurality of thermostats each adapted to function at a predetermined space temperature to cause a portion of said apparatus to operate or cease to operate, an electric heater cooperating with each thermostat to selectively determine the functioning temperature of that thermostat, heater-energizing circuits connected in parallel with one another and a manually operable potentiometer adapted to connect the same selected resistance in series with each of these heaters whereby the entire scale of functioning temperatures is adjusted up or down without changing the spacing between the functioning temperatures of the several thermostats, a resistance in series with certain of the heaters when energized and decreasing the current thereto, and a thermostat functioning at a predetermined temperature outside the space to short-circuit this resistance and increase the temperature at the heaters.

3. In combination with temperature regulating apparatus comprising means for supplying heat to or withdrawing heat from a space, and control mechanism comprising a plurality of thermostats each adapted to function at a predetermined space temperature to cause a portion of said apparatus to operate or cease to operate, an electric heater cooperating with each thermostat to selectively determine the functioning temperature of that thermostat, heater-energizing circuits connected in parallel with one another and a manually operable potentiometer adapted to connectl the same selected resistance in series with each of these heaters whereby the entire scale of functioning temperatures is adjusted up or down without changing the spacing between the functioning temperatures of the several thermostats, a circuit in parallel with certain heaterenergizing circuits, a resistor in said parallel circuit adapted to decrease the current in the heater-energizing circuits, and a thermostat functioning at a predetermined maximum temperature outside the space to close said parallel circuit.

4. In combination with temperature regulatg apparatus comprising means for supplying heat to or withdrawing heat from a space, and control mechanism comprising a plurality of thermostats each adapted to function at a predetermined space temperature to cause a portion of said apparatus to operate or cease to operate, an electric heater cooperating with each thermostat to selectively determine the functioning temperature of that thermostat, heater-energizing circuits connected in parallel with one another and a manually operable potentiometer adapted to connect the same selected resistance in series with each of these heaters whereby the entire scale of functioning temperatures is adjusted up or down without changing the spacing between the functioning temperatures of the several thermostats, a resistance in series with certain of the heaters when energized and decreasing the current thereto, and a thermostat functioning at a predetermined temperature outside the space to shortcircuit this resistance and increase the temperature at the heaters, a circuit in parallel with certain heater-energizing circuits, a resistor in said parallel circuit adapted to decrease the current in the heater-energizing circuits, and a thermostat functioning at a predetermined maximum ternperature outside the space to close said parallel circuit.

5. In combination with apparatus for supplying heat to a space, a thermostat adapted to function at a predetermined space temperature to control said apparatus, an electric heater cooperating with the thermostat to selectively determine the functioning temperature of the thermostat, a resistance in series with the heater to decrease the heating current thereto, and a thermostat functioning at a predetermined temperature outside the space to short-circuit said resistance and thus increase the temperature of the heater.

6. In combination with apparatus for supplying heat to a space, a. thermostat adapted to function at a predetermined space temperature to control said apparatus, an electric heater cooperating with the thermostat to selectively determine the functioning temperature of the thermostat, a resistance in series with the heater to decrease the heating current thereto, and a thermostat functioning at a predetermined temperature outside the space to short-circuit said resistance and thus increase the temperature of the heater, said resistance being closely associated with the last mentioned thermostat and serving when energized to add heat thereto and thus expedite the operation of the thermostat.

7. In combination with apparatus for withdrawing heat from a space, a thermostat adapted to function at a predetermined temperature to control said apparatus, an electric heater cooperating with said thermostat to selectively determine the functioning temperature of the thermostat, a heater-energizing circuit, a circuit in parallel with said energizing circuit, a resistor in said parallel circuit adapted to determine the decrease in the heating current in said heater when the parallel circuit is completed, and a thermostat functioning at a predetermined maximum temperature outside the space to close said parallel circuit.

8. In combination with apparatus for withdrawing heat from a space, a thermostat adapted to function at a predetermined temperature to control said apparatus, an electric heater cooperating with said thermostat to selectively determine the functioning temperature of the thermostat, a heater-energizing ciircuit, a circuit in parallel with said energizing circuit, a resistor in said parallel circuit adapted to determine the decrease in the heating current in said heater when the parallel circuit is completed, a thermostat functioning at a predetermined maximum temperature outside the space to close said parallel circuit, and a heating coil for said latter thermostat connected in said parallel circuit in .series with the resistor.

9. In combination with apparatus for circulating air through a space, apparatus for heating said air, apparatus for withdrawing heat from said air and apparatus for directly adding heat to the air within said space, control means responsive to the temperature of the air in the space at a plurality of spaced temperatures for controlling said apparatuses, each control means comprising a thermostat and an electric heater for adjusting the functioning temperature thereof, and means comprising a thermostat responsive to changes in the temperature of the outside air and a relay controlled by said outside thermostat for cooperating with the inside thermostats to render the cooling means inoperative and both heating means operative below a predetermined outside temperature, and rendering the circulating air heating means and the cooling means operative but the direct heating means inoperative above said outside temperature.

10. In combination with apparatus for circulating air through a space, apparatus for heating said air, apparatus for withdrawing heat from said air, and apparatus for directly adding heat to the air within ssaid space, control means responsive to the temperature of the air in the space at a plurality of spaced temperatures for controlling said apparatuses, each control means comprising a thermostat and an electric heater for adjusting the functioning temperature thereof, and means cooperating with the circulating air heating and cooling means and responsive only to inside temperature changes for rendering both heating means inoperative when the cooling means is operative.

ll. In combination with apparatus for circulating air through a space, apparatus for cooling said air, apparatus for heating said circulated air, and apparatus for directly adding heat to the air within the space, thermostatic control means responsive to changes in the temperature of the air within the space for successively actuating said apparatuses, and means actuated by the combined action of the control means for the cooling apparatus and the control means for the first-mentioned heating apparatus to prevent the effective operation of either heating means while the inside temperature calls for cooling.

l2. In combination with a primary means for heating the air within a space, secondary means for heating said air, control means for each said heating means each comprising a thermostat, a relay, and an electric heater for regulating the functioning temperature of the thermostat, said electric heater being controlled from the relay, the primary heating means being operative below a predetermined space temperature, and the secondary heating means being operative, along with the primary heater, below a predetermined lower temperature, said electric heaters operating independently to vary the functioning temperature of each thermostat, and a circuit also controlled by the relay of said primary heating means for lowering the functioning temperature of the secondary heating means at such times as the primary means is not in operation.

13. In combination with a primary means for heating the air within a space, secondary means for heating said air, control means for each said heating means each comprising a thermostat, a relay, and an electric heater for regulating the functioning temperature of the thermostat, said electric heater being controlled from the relay, the primary heating means being operative below a predetermined space temperature, and the secondary heating means being operative, along with the primary heater, below a predetermined lower temperature, said electric heaters operating independently to vary the functioning temperature of each thermostat. and a circuit also controlled by the relay of said primary heating means for adding current to the electric heater for the secondary thermostat to lower the functioning temperature for the secondary heating means.

14. In combination with a primary means for heating the air within a space, secondary means for heating said air, control means for each said heating means comprising a thermostat, the primary heating means being operative below a predetermined space temperature, and the secondary heating means being operative, along with the primary means, below a predetermined lower temperature, and means also controlled by the control means for the primary heating means for lowering the functioning temperature of the secondary heating means when the primary means is not in operation.

15. In combination with a primary means for heating the air within a space, secondary means for heating said air, control means for each said heating means comprising a thermostat, the primary heating means being operative below a predetermined space temperature, and the secondary heating means being operative, along with the primary means, below a predetermined lower temperature, and means also controlled by the control means for the primary heating means for increasing the operating range of the secondary heating means as the period of operation of the primary heating means is lengthened.

16. In combination with a primary means for heating the air within a space, secondary means for heating said air, control means for each said heating means each comprising a thermostat, a relay, and an electric heater for regulating the functioning temperature of the thermostat, said electric heater being controlled from the relay, the primary heater being operative below a predetermined space temperature, and the secondary heating means normally being operative, along with the primary heater, below a predetermined lower temperature, said electric heaters operating independently to vary the functioning temperatures of each thermostat, and a circuit also controlled by the relay of said primary heating means for lowering the functioning temperature of the secondary heating means at such times as the primary heating means is not in operation, and raising the functioning temperature of the secondary heating means when the primary means is in operation.

17. In combination with a primary means for heating the air within a space, secondary means for heating said air, control means for each said heating means each comprising a thermostat, a relay, and an electric heater for regulating the functioning temperature of the thermostat, said electric heater being controlled from the relay, the primary heater being operative below a predetermined space temperature, and the secondary heating means normally being operative, along with the primary heater, below a predetermined lower temperature, said electric heaters operating independently to vary the functioning temperatures of each thermostat, and a circuit also controlled by the relay of said primary heating means for lowering or raising the functioning temperature of the secondary heating means in proportion to the relative lengths of time that the primary heating means is out of or in operation.

TIMOTHY J. LEHANE. EVERET'I H. BURGESS. 

